Fire extinguisher



July 28, 1931.

} R. w AUSTIN: FIRE EXTINGUISHER Filed April 29, 1927 Patented July 28, 1931 Arsr FIRE EXTINGUISHEB Application filed April 29,

This invention relates to a foam generating fire extinguisher.

The invention has for an object to provide a foam generating fire extinguisher ,of novel 5 and improved construction and which is highly efficient in operation and may be economically manufactured.

A further object of the invention is to provide a novel foam generating fire extinguisher which is capable of. efficient opera'iion at relatively low temperatures.

With these objects in View the invention consists in the foam generating fire extinguisher hereinafter described and particu- I larlv defined in the claims at the end of this specification. I

The drawing illustrates in verticalsection the preferred form of a foam generating fire extinguisher embodying the present invention.

In-the foam generating fire extinguishers now upon the market, a solution of sodium bicarbonate containing a foaming ingredient or agent is received within the usual extinguisher casing. An inner container is supported within the extinguisher casing having a solution of aluminum sulphate contained therein. These materials are normally maintained in separated relation, and

when the extinguisher is operated, the extinguisher casing is inverted, causing admixture of these ingredients with the result that the aluminum sulphate reacts with the sodium bicarbonate to produce carbon dioxide gas resulting in the production of a foam because of the presence of the foamin g ingredient in the bicarbonate solution and also because of the action of the aluminum sulphate on the foam generated in imparting appreciable surface tension to the foam.

The temperature range through which this prior art type of foam generating fire extinguisher may be operated efficiently 1s relatively small, because even at temperatures of 50 F. the generated pressure becomes so low that the operating characteristics of the extinguisher are very poor, and at temperatures in the neighborhood or 40 F. the extinguisher becomes. practically inoperative for lack of pressure. On the other hand When 1927. Serial No. 187,533.

' the operating temperatures reach 100 F., the

pressure becomes excessively high with the result that the quality of the foam is thin and of practically no use for the purpose intended.

I have found that the range of temperature through which a fire extinguisher of the foam generating type may be successfully and efficiently operated, may be appreciably increased by utilizing certain novel reacting materials in such type of extinguisher. I have discovered that phosphoric acid lends itself particularly to use as the acidic solution in a foam generating fire extinguisher in that it imparts a relatively. high surface tension to the foam, rendering the latter stiff and of a character most suitablev for the purpose intended. I have also discovered that a foam generatingfireextinguishercapable of withstanding relatively low temperatures without freezing and of operating efliciently at relatively low temperatures may be produced by utilizing in the extinguisher a carbonate solution containing an hydroxide, I

andinto which solution the foaming agent is introduced, and also utilizing as an acidic solution one capable of withstanding relatively low temperatures without freezing. presence of the hydroxide serves to prevent fermentation or decomposition of the foaming agent, such as licorice, and the heat of re aotionbctween the hydroxide and the acidic The solution when the extinguisher is operated serves to assist in enabling the proper pressures to be developed when the extinguisher is operated under low temperature conditions.

In the preferred form of the present extinguisher, I use a solution of 10 lbs. of potassium carbonate in approximately 2 gallens of water, and in which is dissolved approximately lb. of potassium hydroxide. Into this solution I introduced the foaming agent which may .be licorice or other known foaming agent, and I have had good results with a foaming agent comprising an extract of vhorsechestnuts known in the trade as saponine. This carbonate and hydroxide solution is preferably contained within the extinguisher. casing 10, the latter being preferably composed of steel. For the acidic solution I prefer to employ phosphoric acid, and have had good results With a commercial grade of phosphoric acid, a supply of which is contained Within the usual form of acid bottle 12, supported Within the ,rextinguisher casing upon the usual form of bottle support 13 and having the usual removable stopper 14 normally closing the mouth of the bottle.

The extinguisher is arranged so that when inverted, the acidic solution and the carbon ate solution flow together. The phosphoric acid reacts with the potassium carbonate to generate carbon-dioxidegas, and also reacts with the potassium hydroxide to neutralize the same, generating a large amount of heat. The phosphoric acid also serves to impart relatively high surface tension to the foam, and as a result the foam generated possesses a stiffness in character not possessed by the foam produced by any other extinguisher of which I am aware.

One of the important advantages of the present extinguisher resides in its ability to withstand relatively low temperatures Without freezing. The potassium carbonate solution containing potassium hydroxide Will withstand temperatures as low as -4l0 without freezing, and at the lower temperatures the heat developed by the neutralization of the potassium hydroxide serves to heat the reacting materials and assist in the development of the requisite pressure for the successful and efficient operation of the extinguisher.

The acidic solution of phosphoric acid is also particularly useful in this type of extinguisher in that it possesses the property of imparting relatively high surface tension to the foam generated, and of itself possesses a relatively 10W freezing point, in fact some concentrations thereof have freezing points even as low as -81".

Instead of phosphoric acid solution, other acidic solutions might be used of character having relatively 'low freezing points, and I have found that an acidic solutioncomprising aluminum sulphate with approximately sulphuric acid may be used if desired, ind in such instances the aluminum sulphate functions also to impart additional surface tension to the foam but its action in this respect is not as satisfactory as phosphoric acid.

In order to maintain the acidic solution in zhe acid bottle 12 in a most effective condi- ;ion and to prevent dilution of the acid by ibsorotion of moisture, I preferably provide .1. sealing layer of an inert fluid, preferably icetylene tetra-chloride over the upper surface of the acidic solution. This seal is illus- ;rated in the drawing at 16 and in anti-freez- .ng foam extinguishers it is desirable to employ the seal in order that the freezing point )f the acidic solution may be maintained within the desired limits of temperature.

Having thus described the invention what is claimed is 1. A foam generating fire extinguisher having two normally separated fluids capable of being admixed to generate the foam When the extinguisher is operated, one of such fluids comprising a potassium carbonate solution containing an hydroxide and a foaming agent, and the other of such fluids comprising phosphoric acid solution.

2. In a foam generating fire extinguisher, tWo normally separated fluids capable of being admixed to generate the foam, one of said fluids comprising a phosphoric acid solution.

3. In a foam generating fire extinguisher, tWo normally separated fluids capable of being admixed to generate the foam, one of said fluids comprising a solution of potassium carbonate and potassium hydroxide and containing a foaming agent, and the other of said fluids comprising a phosphoric acid solution, both fluids being of a concentration having a relatively low freezing point.

In testimony whereof I have signed my name to this specification.

RALPH IV. AUSTIN. 

